Interactive app puts a handle on blackleg

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A new app, BlacklegCM, should help growers better predict and ultimately manage yield and gross margin losses from blackleg disease in canola.

Oilseed pathologist Steve Marcroft says the app (for tablets) has an interactive interface that allows growers to enter paddock-specific information. This on-farm data enables growers to more accurately determine the efficacy of different blackleg management options on a paddock-by-paddock basis before planting canola.

In particular, the BlacklegCM app forecasts the likelihood and severity of blackleg pressure, the yield loss likely to result, the cost and potential yield benefits of different control options and the gross margin return.

Photo of Steve Marcroft (left) and Craig Drum
Canola pathologist Steve Marcroft (left) demonstrates the new BlacklegCM app to Tatyoon Rural agronomist Craig Drum. PHOTO: Clarisa Collis

“There was a need for a management tool that can forecast disease based on management principles proposed for an individual paddock and this led to the development of the BlacklegCM app,” Dr Marcroft says.

He says the app is an extension of the GRDC’s Blackleg Management Guide, which is updated twice a year to reflect frequent changes in the blackleg resistance status of canola varieties. “Although the guide provides useful information, it has some limitations,” Dr Marcroft says. “For example, it is difficult to consider complex interactions, such as the performance of cultivars with different blackleg resistance ratings in high and low-rainfall environments.”

The new app, however, integrates information contained in the guide with on-farm data entered by growers to help isolate and compare the profitability of individual disease control measures.

Examples of these control measures are paddock selection and cultivar choice, as well as fungicide seed dressing, banding and spraying.

“Using BlacklegCM, growers can explore options for disease control and understand the economic importance of each control measure.”

Highlighting the impact of paddock selection on blackleg pressure, for instance, Dr Marcroft says, “a canola crop’s distance to one-year-old stubble has a large influence on disease severity, while two-year-old stubble has less influence”.

The GRDC-funded app also allows growers to predict the efficacy of different control options when they are used in combination as part of an overarching blackleg control strategy. This means growers can mix and match blackleg control measures to optimise the crop’s gross margin.

“For example, foliar fungicide has a limited impact on blackleg, but it is very effective if used in combination with a seed dressing fungicide,” he says.

He says the new tool can also be used during the growing season to help growers tailor their blackleg management strategies to variable seasonal conditions. “In 2016, many growers planned for a two-tonne-per-hectare canola crop, but later realised their yield potential was much higher. Members of the National Canola Pathology Program then warned of severe pressure from blackleg lesions.

“In this scenario, during July of that year, growers could have re-run the app entering a revised 3t/ha yield target and compared the outcomes with and without foliar fungicide use. This is important because foliar fungicide use on a 1t/ha crop is likely to cause economic loss, but when used on a 3t/ha crop it is likely to result in a large profit.”

Dr Marcroft says the app, available through the App Store and Google Play Store, will be regularly updated to ensure it covers all current canola cultivars and their blackleg resistance ratings. “All new knowledge will be incorporated, including information on upper canopy infection and different timings for fungicide applications,” he says.

“So the app will continue to grow and evolve with the canola industry, and it is expected to become the mainstay for blackleg knowledge in Australia.”

BlacklegCM was developed through the Western Australian Department of Primary Industries and Regional Development, with input from all members of the GRDC’s National Canola Pathology Program.

More information:

Steve Marcroft
03 5381 2294
0409 978 941
steve@grainspathology.com.au

Autumn 2018 Blackleg Management Guide